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Comment by devindotcom | Hacker News Reader

I talked with Intel's director of quantum hardware about this.

https://techcrunch.com/2017/10/10/intel-moves-towards-produc...

What they're really proud of is essentially bringing Intel's manufacturing advantage to bear on an extremely new and different form of computing. Being able to iterate with new materials and architectures every few months is critical for testing, and it's there (as opposed to sheer numbers of qubits or whatever) that Intel hopes to outstrip the competition.

I was also surprised to learn that the cryo systems that get things down to a fraction of a kelvin are only the size of 50-gallon drums. I was picturing something much larger for anything that low. Now I know!

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We owe it to Particle accelerators and MRI machines to let us cool to those temperatures. I also find it surprising that it is as small as a 55 gallon drum.

Amazing how this has progressed: in high school I was in a summer program with the guy who won the Science Talent Search that year with the research he was collaborating on in Nuclear Magnetic Resonance. (Note that the "Nuclear" has been removed from the tech for essentially PR reasons).

> only the size of 50-gallon drums.

Wow. I could see something that size as per-workspace for specific use cases. Though what those use cases might be, I don't know. (Also, cost is probably the prohibitive factor right now...)

Still, I'd always imagined that quantum computers would start out as something that could only be done mainframe-like due to size. Perhaps not!

> I was also surprised to learn that the cryo systems that get things down to a fraction of a kelvin are only the size of 50-gallon drums. I was picturing something much larger for anything that low. Now I know!

Contrast that to the cooling D-Wave uses. It's not all cooling but it gives you an idea of the cooling apparatus: https://youtu.be/zDotDiK2UuY?t=50

Nah it's exactly the same.

It's not really just the size of a 50 gallon drum. There's the helium compressor, all the pumps, the cold trap, the valve cabinet, keg, etc.

Would be fascinated to hear anything you (or anyone in a related field) has to say on the challenges for cooling to such low temperatures.

Is it essentially just heat-removal + lots of layers of isolated, effective insulation, or are there fundamental differences when you're going that low?

I'm not sure about what's used in all industry applications, but this video explains one implementation of a super-cooling setup: https://www.youtube.com/watch?v=7jT5rbE69ho.

I won't even try to summarise it - I'm sure I'd get it wrong! Fascinating stuff though.

I worked with NMR about 8 years ago in the uni. We used regular liquid helium to get to about 4.2 degrees K. The next step is He 3 isotope which is an order of magnitude more expensive but gets you an order of magnitude cooler (in degrees K). That usually runs in a closed system (heated He is not vented into the atmosphere) because of its cost.

The way cooking it was explained to me is that you try to slow down atoms with lasers, but I don’t know any of the details.

From memory: you fire a laser at a frequency that is only absorbed if relatvistically shifted the way an electron that goes towards the laser would observe. This, the laser delivers momentum only to atoms coming towards it, and is invisible to those at rest or going away. Do from multiple directions and you’ve reduced absolute momentum in every direction.

Claude Cohen danucci received a nobel and a wolf for this (and other things)

https://en.wikipedia.org/wiki/Doppler_cooling

I work in this exact field. Yes. It's essentially a thermos. There's several cans nested within each other. Each can hangs from a different refrigeration stage. Typically you go from 300 K (the outer vacuum can), to 77 K (first pulse tube stage), to 4K (second pulse tube stage), then to 300 mK (still of dilution unit), then to base at 10 mK, though the 10 mK stage doesn't have it's own can. Everything is copper or gold plated copper where you want heat to flow, or G-10 (fiberglass) or stainless steel where you don't. There's mechanisms for thermally shorting stages together... sometimes it's a mechanical gripper that pinches an extension from a colder stage, other times it's stainless steel tubing that gets filled with gas (the heat conducting material) when you want to transfer heat, and then evacuated when you don't.

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